3. 无重复字符的最长子串(leetcode)

https://leetcode.cn/problems/longest-substring-without-repeating-characters/description/

同向双指针问题,利用hashmap判重

class Solution {int res;public int lengthOfLongestSubstring(String s) {Map<Character,Integer> map = new HashMap<>();char[] strs=s.toCharArray();for(int i=0,j=0;i<strs.length;i++){map.compute(strs[i],(k,v) -> v==null ? 1:v+1);while(map.get(strs[i]) > 1) // 判断是否有重复,重复元素只能是新加入的strs[i]发生重复{map.compute(strs[j],(k,v)-> v-1);j++; //缩小范围}res=Math.max(res,i-j+1);}return res;}
}